Post-forming machine



Sept. 22, 1964 A. LEE

POST-FORMING MACHINE 6 Sheets-Shget l INVENTOR. ANDREW LEE BY MW M ATTORNEYS Filed Aug. 2 1963 Sept. 22, 1964 A. LEE 3,149,376

POST-FORMING MACHINE Sept. 22, 1964 A. LEE 3,149,376

POST-FORMING MACHINE INVENTOR.

M} I 7 ANDREW LEE ATTORNE YS Sept. 22, 1964 L 3,149,376

POST-FORMING MACHINE Filed Aug. 28, 1963 6 Sheets-Sheet 5 R m. mQ

Sept. 22, 1964 A. LEE

POST-FORMING MACHINE 6 Sheets-Sheet 6 Filed Aug. 28, 1965 INVENTOR. A/vamsw LEE AT ToRA/grs Qt avin:

United States Patent M 3,149,376 POST-FORMING MACHDJE Andrew Lee, Top-Fab Co., 2900 14th Ave. S., Minneapolis, Minn. Filed Aug. 28, 1963, Ser. No. 305,091 9 Claims. (Cl. 18-19) My invention relates generally to bending apparatus, and more particularly to a machine for post-forming flat sheets of plastic C-stage thermo setting resinous material.

More specifically, my invention relates to machines for forming flat sheets of such plastic material 1Ilt01COVFF ings for counter tops, drain boards and the like, hav ng base structures of wood, metal or any suitable material, such plastic covering material being commercially avail; able under such trade names as Formica, Micarta and others.

Heretofore, in the post-forming of a counter top or drain board to provide a generally horizontally disposed deck portion, a generally vertically disposed splash back portion, and raised or curved edge portions, it has been customary to adhere spaced backing sheets and strips of wood or other suitable material to the back of the plastic sheet when the same is in fiat form, and thereafter to post form the plastic sheet in the areas between the backing sheets and strips. After forming, additional filler strips or the like are adhered to the back of the formed sheet, at the bent portions thereof, to reinforce the same. This procedure is time consuming and costly, and necessitates accurate placement of the backing sheets and strips prior to the post forming operation. The primary ob ect of my invention is therefore, the provision of a machine for post-forming laminated plastic sheets of the type aforesaid without the necessity for first applying backing sheets, strips and the like to said sheets. i

Another object of my invention is the provision of a post-forming machine which forms plastic sheets with a high degree of uniformity and accuracy.

Another object of my invention is the provision of a post-forming machine in which a plurality of bends are made in a flat plastic sheet automatically and substantially simultaneously, whereby to effect a substantial savings in time and effort.

Still another object of my invention is the provision of a post-forming machine, as set forth, which is quickly and easily adjustable to accommodate work pieces of various dimensions.

Another important object of my invention is the provision of a post-forming machine having heated forming dies so shaped and disposed relative to the workpiece that heat is transferred to the workpiece in a minimum of time and with a maximum of efficiency.

A still further object of my invention is the provision of novel control means whereby the timing and speed of the forming or bending operation is maintained at the optimum consistent with good molding practice.

The above, and still further highly important objects and advantages of my invention will become apparent from the following detailed specification, appended claims and attached drawings.

Referring to the drawings, which illustrate the invention, and in which like reference characters indicate like parts throughout the several views:

FIG. 1 is a view in side elevation of a post-forming machine produced in accordance with my invention, some parts being broken away;

FIG. 2 is a view in side elevation opposite that of FIG. 1, some parts being broken away;

FIG. 3 is an enlarged view in end elevation, as seen from the right with respect to FIG. 1

FIG. 4 is a view in horizontal section, taken substan- 3,149,376 Patented Sept. 22, 1964 tially on the line 4-4 of FIG. 3, some parts being broken away;

FIG. 5 is an enlarged fragmentary section taken on the line 5-5 of FIG. 3;

FIG. 6 in an enlarged fragmentary vertical section taken on the irregular line 66 of FIG. 2;

FIG. 7 is an enlarged fragmentary detail partly in side elevation and partly in section, taken on the line 7-7 of FIG. 4, some parts being broken away;

FIG. 8, Sheet 2, is an enlarged fragmentary section taken on the line 8-8 of FIG. 4;

FIG. 9, Sheet 1, is an enlarged fragmentary detail in perspective showing a portion of a forming die operating mechanism of my invention;

FIG. 10 is a diagrammatic view illustrating the fluid pressure operating mechanism and control system therefor, of my invention; and

FIG. 11, Sheet 3, is a fragmentary view in perspective showing a sheet of plastic material subsequent to the forming thereof in my post-forming machine, and applied to a prefabricated backing structure.

In the preferred arrangement of my post-forming machine illustrated, a flat sheet of C-stage laminated plastic material, indicated in its entirety by the reference character A, is formed to provide a flat horizontally disposed deck portion B, an upstanding splash-back portion C, an upper curved edge portion D, a nose portion E at the front edge portion of the deck B, and a skirt portion F projecting downwardly from the nose portion E, see particularly FIG. 11. The sheet A is formed into the shape shown in FIG. 11 independently of backing sheets or strips, and subsequent to forming is adhered to a prefabricated supporting structure that is built to conform to the contour of the formed sheet A. The supporting or backing structure, indicated by the reference character G in FIG. 11, is preferably made from wood, but may be made from any suitable material.

The post-forming machine of my invention involves a supporting frame, indicated generally by the numeral 1, and comprising laterially spaced pairs of longitudinally spaced supporting legs 2 and 3 mounted on caster wheels or the like 4, a pair of laterally spaced longitudinal frame members 5 and 6 rigidly secured to the upper ends of the legs 2 and 3 respectively and braced by respective angular brace members 7 and 8, transverse end frame members 9 connecting adjacent ends of the longitudinal frame members 5 and 6, and intermediate cross frame members 10. A pair of horizontally disposed transverse brace bars or the like 11, one of which is shown, connect each supporting leg 2 with an adjacent supporting leg 3, see FIG. 3.

An elongated workpiece supporting table 12 extends longitudinally of the frame structure 1 and comprises a pair of laterally spaced parallel structural channel members 13 and 14 the former of which is welded or otherwise rigidly secured to the longitudinal frame member 5 and transverse frame members 9 and 10. The channel member 14 is rigidly secured to an elongated supporting plate 15 which rests upon the transverse frame members 9 and 10, each of the channel members 13 and 14 being provided with horizontally disposed plate-like elements 16 and 17, one of which overlaps the other, and both of which are supported by an intermediate supporting beam 18 that is bolted or otherwise rigidly secured to the transverse frame members 9 and 10. The channel members 13 and 14 with their respective plate-like elements 16 and 17 comprise table sections, the section including the channel 14 and plate-like element 17 being movable transversely of the frame structure 1 toward and away from the section including the channel 13 and platelike element 16. Means for adjustably moving the channel 14 and plate-like element 17 transversely of the frame structure 1 comprises a pair of threaded shafts 19 that are journalled at one end in bearings 20 mounted on brackets 21 that are bolted or otherwise secured to the longitudinal frame member 5, the shafts 19 having stop collars or the like 22 at opposite sides of the bearings 20 to prevent longitudinal movement of the shafts 19 relative to their respective bearings 20. The shafts 19 have screw'threaded engagement with nut-like elements 23 that are bolted or otherwise rigidly secured to the mounting plate 15, and at their outer ends are each provided with sprocket wheels 24 having an endless link chain 25 entrained thereover. As shown in FIGS. 24, one of the threaded shafts 19 is provided with a crank 26 for manually rotating both of the shafts 19 through the medium of the sprocket wheels 24 and endless link chain 25. As shown in FIGS. 3 and 6, the channels 13 and 14 are provided at their upper surfaces with wear strips or plates 27 and 28 respectively, for a purpose which will hereinafter become apparent.

For the purpose of securely clamping a sheet A of the material to be formed on the table 12, I provide a first clamping mechanism involving an elongated channel beam 29 that overlies the channel 13 and which is provided at its bottom with a horizontally disposed longitudinally extending pressure plate 30, and has welded or otherwise rigidly secured thereto a plurality of vertically disposed transversely outwardly extending webs 31 spaced longitudinally of the beam 29. The beam 29 is supported by a pair of longitudinally spaced transverse arms 32 that are rigidly secured at their outer ends to depending tubular legs 33 that extend downwardly through guide tubes 34 welded or otherwise rigidly secured at their lower ends to horizontally disposed supporting beams 35 that extend laterally outwardly from the legs 2 and which are reinforced by brace members or the like 36. The guide tubes 34 are formed to provide circumferentially spaced openings 37 and radially outwardly projecting cars 38 on opposite sides of the openings 37 and in which are journalled guide rollers 39 that engage the legs 33 to provide for smooth axial movement of the legs 33 within the guide tubes 34. A pair of vertically disposed fluid pressure cylinders 40 are mounted on brackets 41 secured to the guide tubes 34, and are provided with pistons 42 and cooperating piston rods 43 that are connected to lugs 44 welded or otherwise rigidly secured to the upper ends of the legs 33, see particularly FIGS. 1 and 3. Fluid, such as air, is introduced to the bottoms of the cylinders 40 from a source of pressure not shown, through conduits 45 and other means to be hereinafter described, to elevate the channel beam 29 and parts associated therewith, away from engagement with the plastic sheet or workpiece A on the table 12. Air under pressure is admitted to the upper ends of the cylinders 40 to lower the clamping channel beam 29 and parts associated therewith, through conduits 46. A second clamping mechanism is carried by the mounting plate for common lateral movements with the table section in-' volving the channel 14 and plate-like element 17, and comprises an elongated clamping member 47 which extends longitudinally of the frame structure 1 in overlying relation to the channel 14 and wear strip 28 and which is mounted on an elongated channel beam 48. A pair of 1011' gitudinally spaced inverted generally U-shaped members 49 comprise laterally inner and outer depending legs 50 and 51 respectively, the former of which are welded or otherwise rigidly secured to the channel beam 48 and braced by diagonal brace bars or the like 52. The laterally outer legs 51 are of generally cylindrical outline, and extend axially through respective ones of a pair of tubular guides 53 that are rigidly secured at their lower ends to laterally outwardly projecting supporting bars or channels 54 that are welded or otherwise rigidly secured at their inner end portions to the mounting plate 15, each adjacent a different one of the intermediate frame members 10. The tubular guides 53 are substantially identical to the guide tubes 34, having axially spaced groups of circumferentially spaced openings 55 therethrough and radial ears 56 in which are journalled rollers 57 that engage circumferentially spaced surface portions of the legs 51 to support the same, see particularly FIG. 4. As will be seen, with reference to FIGS. 2 and 4, that the close proximity of the supporting bars 54 to adjacent ones of the intermediate frame members 10 permits laterally inward and outward movements of the mounting plate 15 and parts carried thereby, when the crank 26 is turned, but limits movement of the mounting plate 15 and parts carried thereby in a direction longitudinally'of the frame structure 1, the edges of the frame members 10 serving as guides for the supporting bars 54 during laterally inward and outward movements of the mounting plate 15.

Means for raising and lowering the clamping member 47 and parts associated therewith, relative to the table 12, comprises a pair of vertically disposed fluid cylinders 58 that are secured one each to a different one of the tubular guides 53 by means of brackets or the like 59. Each of the cylinders 58 is provided with a piston 60 and a cooperating piston rod 61 that extends upwardly from its respective cylinder 58 and is connected at its upper end to a lug 62 projecting laterally outwardly from an adjacent one of the legs 51 at the upper end thereof. As with the cylinder 48, fluid, such as air under pressure, is introduced to the lower ends of the cylinders 53 through conduits 63 to raise the clamping member 47, said fluid being introduced to the upper end of the cylinder 58 through other conduits 64 to lower the clamping member 47 into engagement of the workpiece A.

The clamping member 47 is in the nature of a forming die that is rigidly secured to a bracket 65 by means of.

mounting screws 65', the bracket 65 being welded or otherwise rigidly secured to the channel beam 48. T he clamp ing member or forming die 47 has tapering opposite side surfaces which terminate in a cross sectionally arcuate surface 66 that engages the top surface of the workpiece or plastic sheet A to hold the same against the wear strip 28. Further, the forming die 47 is provided with a conventional heating element 67 whereby the forming die 47 is maintained at the proper temperature for softening the engaged portion of the workpiece A to enable the same to be formed. It will be noted, by reference to FIG. 3, that the arcuate surface 66 tangentially engages the top surface of the workpiece A, so that heat radiating from the forming die 47 is directed toward the workpiece A at opposite sides of the line of tangential engagement therebetween.

For properly locating the workpiece or sheet A transversely of the machine, I provide a pair of abutment members 68 that are provided with transverse shafts 69 which are longitudinally adjustably mounted in tubular brackets 70 that are welded or otherwise rigidly secured each to a different one of the tubular guides 53, see particularly FIGS. 3 and 6. As shown in FIG. 3, when the workpiece A is placed in the machine for forming, one longitudinal edge thereof is disposed in engagement with the abutment elements 68.

A pair of second and third forming dies 71 and 72, similar to the clamping member or forming die 47, are elongated in directions longitudinally of the machine and are disposed at opposite sides of the table 12. The form-. ing dies 71 and 72 are substantially identical, each thereof having laterally outwardly converging sides which terminate in a cross sectionally arcuate work piece engaging surface 73, each of the forming dies 71 and 72 being heated to a predetermined degree by conventional heating elements 74. Each of the second and third forming dies are rigidly mounted on respective elongated mounting members 75 and 76 by means of longitudinally spaced mounting screws 77 and spacing blocks 78. Intermediate the spacing blocks 78, the forming dies 71 and 72 have screw threaded therein a plurality of longitudinally spaced adjusting screws 79, the heads of which engage underlying portions of their respective mounting members 75 and 76 to brace the forming dies 71 and 72 against warping during heating and cooling thereof. The mounting members 75 and 76 are each hinged to an adjacent one of the channels 13 and 14 as indicated at 8%) and 81 respectively, for swinging movements between retracted positions as shown in FIG. 3, and projecting material forming positions illustrated in FIG. 6. It will be noted with reference to FIG. 3, that, like the first mentioned forming die 47, the arcuate surfaces 73 of the second and third forming dies 71 and 72 make tangential contact with the adjacent undersurface portions of the workpiece A, heat being directed toward the workpiece A at opposite sides of the line of tangential contact between the workpiece A and the arcuate surfaces 73.

Cooperating with the second forming die 71 to initially move the adjacent side edge portion of the workpiece A into engagement with the arcuate surface 73 of the second forming die 71 in the retracted position thereof, and to form the side edge portion of the workpiece A to provide the nose E and skirt F thereof, is an elongated workpiece engaging member 82. The member 82 is mounted on a mounting bracket 33 in the nature of a length of structural angle iron for adjustment laterally thereof by means of screws 84 extending through slots 85 in the bracket 83. The bracket 85 is mounted for lateral adjustment on a plurality of angle members 85, by means of nut-equipped screws or the like 87, the angle members as being pivotally secured to adjacent ones of the webs 31, as indicated at 83.

Nut-equipped screw and slot connections 89 are used to anchor the angle members 86 and parts carried thereby in desired adjusted positions relative :to the second forming dies 71.

As shown in FIG. 3, when the angle beam 29 and parts associated therewith are lowered into clamping engagement of the pressure plate 30 with the workpiece A, the workpiece engaging member 82 bends the underlying portion of the workpiece A downwardly into tangential engagement with the arcuate surface 73 of the second forming die 71, whereby the portion of the workpiece A engaging the second forming die 81 immediately begins to be heated toward a softened state. As above indicated, heat radiating from the arcuate surface portion 73 is also directed to the adjacent portion of the workpiece or sheet A laterally outwardly of both sides of the line of tangential engagement between the sheet and second forming die. This occurs with the second forming die in its lower or retracted position below the level of the top of the table 12. The third forming die in its lower or retracted position shown in FIG. 3, has its arcuate surface portion 73 disposed slightly above the level of the top of the table 12 and, when the clamping member or first forming die 47 is lowered into clamping engagement with the workpiece or sheet A, a portion of the sheet A laterally outwardly of the forming die 47 is bent slightly upwardly by tangential engagement therebetween and the third forming die 72, whereby that tangentially engaged portion of the sheet A is heated by the heated forming die 72 in the same manner as described above in connection with the forming die 71. As will be hereinafter more fully described, a second workpiece engaging member 9%, comprising an angle bracket 91 extending longitudinally of the channel beam 4?, and vertically adjustably bolted thereto, and a laterally outwardly projecting extension 92, cooperate with the third forming die 72 to form the adjacent edge portion of the plastic sheet A.

For the purpose of imparting movements to the second and third forming dies 71 and 72 from their retracted positions of FIG. 3 to their generally upwardly projected positions of FIG. 6 to post-form the plastic sheet A, I provide a pair of fluid pressure cylinders 93 and 94 and connections therebetween and their respective forming dies 71 and 72, now to be described. The cylinders 93 and 94 are mounted respectively on the channel 13 and mounting plate by means of brackets 95 and 96 respectively, and are each provided with pistons 97 and cooperating piston rods 98. The piston rods 98 and the connection therebetween and respective forming dies 71 and 72 are identical, said connections being identified by like reference characters and one thereof being described. Each piston rod 98 comprises a portion of piston rod structure involving bifurcated rod sections 99 and 100, the former of which is connected to the piston rod 98, as indicated at 101. The rod sections 99 and 100 are disposed in alignment the adjacent ends thereof being adjustable connected by means of a conventional turn buckle 102. The rigid bifurcated rod sections 99 and 1013 are provided with laterally inner and outer rollers 103 and 104 respectively, the latter of which are adapted to ride against respective ones of the channel 13 and mounting plate 15, the inner rollers 103 overlying longitudinally extended slots 105 in the channel 13 and in the mounting plate 15, see FIGS. 4 and 7. The inner rollers 103 operate as cam follower rollers, those of the rod sections 99 and 1% associated with the cylinder 93 bearing against triangular cams 106 which project through the slots 105 in the channel 13 and which are hingedly mounted to the forming die mounting member 75, as indicated at 197. The inner rollers 103 of the rod sections 99 and 1% associated with the cylinder 94 likewise engage triangular cams 108 which are similar to the cam 11% and which are hingedly connected to the mounting member 76, as indicated at 109, in the same manner that the cams 1136 are hinged to the mounting member 75. The cams 106 and 103 are so arranged that movement of the piston rods 98 to the right with respect to FIGS. 2, 4 and 7, will cause the second and third forming dies 71 and 72 to move toward their projected positions of FIG. 6; whereas movement of the piston rods 98 to the left with respect to FIGS. 2, 4 and 7 will permit the second and third forming dies 71 and 72 to descend to their retracted positions of FIG. 3 by gravity. It will be noted that each of the piston rod structures is provided with a plurality of the cam follower rollers 1134 in spaced relationship axially relative to the piston rods 98; and that the mounting members 75 and 76 are each provided vn'th a like plurality of cams 106 and 108 respectively in spaced relationship longitudinally of their respective mounting members 75 and 76, whereby even pressure is exerted on said mounting memers forming die projected directions along substantially the entire length of the mounting members 75 and 76 respectively.

In the post-forming of the workpiece A, it is desired that the second and third forming dies 71 and 72 respectively move toward their projected positions of FIG.

6 at a relatively slow rate and that said second and third forming dies move toward their retracted positions of FIG. 3, after the post-forming operation is completed at a relatively rapid rate. To achieve this function, I provide a pair of identical hydraulic check devices 110 and 111, the former of which is operatively connected to the piston rod structure of the cylinder 93 and the other of which is connected to the piston rod structure associated with the cylinder 94. As shown in FIG. 5, each of the check devices 110, 111 comprises a cylinder 112 that is rigidly mounted to its adjacent beam 13 or mounting plate 15 and has axially slidably mounted therein a cooperating piston 113 connected to a piston rod 114 which extends axially outwardly from one end of the cylinder 112 in a direction longitudinally of the arm sections 99 and 100, being rigidly connected to the adjacent end of the rod section 100, as indicated at 115. The piston 113 is provided with a plurality of fluid passages 116 which extend am'ally therethrough and which are adapted to be closed by a spring pressed check valve plate 117. The opposite ends of the cylinder 112 are connected by a fluid passage 118 having a metering valve 119 for adjustment of fluid flow through the passage 118. A fluid reservoir is also provided, comprising a cylinder 120, and a cooperating spring pressed piston 121 having a pin 122 extending axially outwardly from one end of the cylinder 120 to indicate the amount of fluid in the check device. During movement of the pistons 97 in their respective cylinders 93 and 94 in a direction to move the second and third forming dies 71 and 72 toward their projected positions, the pistons 113 are moved in a'direction'from the right to the left with respect to FIG. 5. In this direction of movement of the pistons 113, the check valves 117 are closed and all of the fluid flow from the left hand end of the cylinders 112 to the right end thereof is through the passages 118, at a relatively slow rate dependent upon the adjustment of the metering valves 119. When the pistons 97 move in the opposite direction to permit retracting movements of the second and third forming dies 71 and 72, the piston 113 moves to the right with respect to FIG. 5, pressure in the right hand end of the cylinder 112 causing the check valves 117 to open to permit relatively free flow of fluid through the passages 116 toward the left hand end of the cylinders 112. Thus, the forming dies 71 and 72 are permitted to return rapidly to their retracted positions of FIG. 3. Each complete operating cycle of the present machine is manually initiated, after which each function of the machine is automatically controlled and the operating cycle completed by control means now to be described. With reference to the diagram of FIG. 10, it will be seen that the conduits 45 and 63 are connected to a common fluid conduit 123, and that the conduits 46 and 64 are connected to a common conduit 124, which conduits lead to a reversing valve 125 which includes a generally cylindrical housing 126, an axial movable valve element 127 in the housing 126,and a piston 128 connected to the valve element 127 and yieldingly urged in a direction to move the valve element 127 in one direction of its axial movement by a light coil compression spring or the like 129. The valve element 127 is movable in the opposite direction by an operating handle 130, against bias of the spring 129. It should here be noted that the spring 129 is not of sufiicient strength to move the valve element 127, but will maintain the element 127 in its raised position shown in FIG. 10. The housing 126 is provided with a port 131 leading to atmosphere and a second port 132 that is connected to a source of fluid such as air, by means of a conduit 133, said source being conventional and not shown. The conduit 133 also leads to a reversing valve 134 comprising a generally cylindrical 'body'135 and a valve spool or the like 136 axially movable therein. A conduit 137 leads from the valve 134 to atmosphere through a conventional metering valve 138; and a pair of conduits 139 and 140 lead from the valve 134 to opposite ends of the cylinders 93 and 94. A conduit 141 is connected between the conduit 133 and the valve housing 126 below the piston 128 and has interposed therein a valve 142 comprising a valve body 143 and a valve spool 144 axially movable therein and yieldingly urged in one direction of its movement by a spring 145. A solenoid 146 is connected to the valve spool 144 to move the same in the opposite direction against bias of the spring 145. Energization of the solenoid 146 causes movement of the valve spool 144 in a direction to permit fluid under pressure to flow from the conduit 133 to the piston 128 to move the same upwardly. Deenergization of solenoid 146 permits the spring 145 to move the valve spool 144 in a direction to exhaust fluid from the valve housing 126 below the piston 128 to atmosphere through a port or passage 147. A pair of reversing valve operating devices are shown as being in the nature of valves 148 and 149 comprising housings 150 and 151 respectively, valves 152 and 153 respectively, operating solenoids 154 and 155 respectively and respective return springs 156 and 157. Each of the valves 148 and 149 are connected to the pressure line or conduit 133, as indicated at 158 and each is connected to an opposite end of the reversing valve 134 by a respective conduit 159 and 160, each of said valves 148 and 149 further having a port 161 to atmosphere. Fluid pressure controlled timing devices 162 and 163 are interposed in respective ones of the conduits 159 and 166, and operate as time delay elements for admitting air under pressure to adjacent ends of the reversing valve 134. The timing devices 162 and 163 may be any one of several commercially available types such as the universal timing sequence head such as produced by Bellows-Valvair Company of Akron, Ohio, under the trademark Valvair. When air under pressure is introduced to one side of the timing devices 162 and 163, a predetermined time interval occurs before the air is permitted to flow through'the timing device to an adjacent end of the reversing valve 134.

Means for operating the several solenoids 146, 154 and comprising electrical control circuit means including said solenoids and a plurality of control switches. One such switch is a normally open switch, 164 that is mounted on one of the tubular guides 53 and which is adapted to be closed as the clamping member or first forming die 47 moves into clamping engagement with the workpiece A against the channel 14. A pair of normally open switches 165 and 166 are mounted on the bracket 95 and are closed by movement of the piston rod 98 associated with the cylinder 93 in opposite directions, by means of a switch operating finger 167, the switches 165 and 166 being of the momentary contact variety. Another pair of normally open momentary contact switches 168 and 169 are mounted on the mounting plate 15 and are adapted to be closed by a switch operating finger 17% that is mounted on the piston rod 98 associated with the cylinder 94. The switch 168 is provided with an operating linkage 171 which permits passage of the operating finger 170 thereover in a direction from the left to the right with respect to FIG. 10 without closing the switch 168. However, when the finger 170 engages the linkage 171 during its movement from the right to the left, the switch 168 will be momentarily closed.

It will be noted that switches 164 and 165 and the solenoid 154 are connected in a series circuit with a twoconductor power line 172. The switches 164, 166 and 169, and the solenoid 155 are disposed in series in a second circuit. The switch 168 and solenoid 146 are connected in series in a third circuit to the power line 172, a manually operated main switch 173 being interposed in all of said circuits. Although not shown, it may be assumed that the heating elements 67 and 74 are disposed in circuits energized by the power line 172 and controlled by the switch 173, in the usual manner.

Assuming that the switch 173 is closed and that the various pistons 42, 60 and 97 are as shown in FIG. 10, whereby the workpiece clamping elements 29 and 47 are raised, as shown by dotted lines in FIG. 3 and that the second and third forming dies 71 and 72 are retracted, the operator places a sheet A to be formed on the table 12 and beams 13 and 14, with one side edge of the sheet engaging the abutment members 68. He then depresses the valve operating lever 130 to cause air under pressure to be delivered from the conduit 133 through the conduits 124, 46 and 64 to the tops of the cylinders 40 and 58, causing the pressure plate 30 and first forming die 47 to securely clamp the plastic sheet A against the underlying wear strips 27 and 28. on the beams 13 and 14. As the U-shaped members 49 carrying the firstforming die 47 approach their limit of downward movement, one thereof closes the switch 164 to cause energization of the solenoid 154, moving the valve spool 152 in a direction to admit air under pressure through a portion of the conduit 159 to the timing device 162. During the time interval for which the timing device 162 is set, for instance, an interval of ten seconds, the portions of the plastic sheet A engaged by the forming dies 47, 71 and 72 are becoming heated and softened to a post-formable state. At the completion of the time interval, the timing device 162 operates to admit air under pressure to the right hand end of the reversing valve 134 to cause movement of the spool 136 to the opposite end of the valve body 135, thus causing air under pressure to be admitted to the left hand ends of the cylinders 93 and 94. Consequent movement of the pistons 97 toward the right with respect to FIG. causes the second and third forming dies to move toward their projected forming positions of FIG. 6, the rate of this movement being controlled by the hydraulic checks 110 and 111, The second forming die cooperates with the outer lateral edge of the pressure plate 31) and the workpiece engaging member 82 to form the nose and skirt portions E and F of the workpiece A; whereas, the third forming die 72 cooperates with the first forming die 47 and the second workpiece engaging member 91) to form the substantially vertically disposed splash back portions C and curved edge portion D of the sheet A. It will be noted with reference to FIG. 6 that the skirt and splash back portions of the plastic sheet are bent slightly more than to vertical positions. However, when the workpiece is subsequently removed from the machine, the inherent resilience of the material causes the skirt and splash back portions to be substantially normally disposed with respect to the plane of the deck portion B of the sheet A. It should be here noted that, as the pistons 42 and 69 move downwardly to lower the clamping members into engagement with the workpiece, air from the bottoms of the cylinders 46 and 53 is released to atmosphere through the conduits 45, 63 and 123 and exhaust port 131. Likewise, as the pistons 97 move toward the right in their respective cylinders 93 and 94, air at the right hand end of these cylinders is exhausted through the conduit 140, valve spool 136 and conduit 137 and valve 138.

When the pistons 97 reach their limit of forming die projecting movement to the right with respect to FIG. 10, the fingers 167 and 17% close the switches 166 and 169 respectively to cause energization of the solenoid 155. Such energization of the solenoid 155 causes the valve spool 153 to be positioned to admit air under pressure to the timing device 163 which, after a predetermined time interval to permit the second and third forming dies to remain in their projected positions of FIG. 6, admits the air under pressure to the left hand end of the valve housing 135 to move the valve spool 136 to the right with respect to FIG. 10. With the valve spool 136 thus positioned, as shown in FiG. 10, air under pressure is delivered through the conduits 149 to the right hand ends of the cylinders 93 and 94 to impart movement to the pistons 97 toward the left with respect to FIG. 10. During this movement of the pistons 97, the check valves 117 in the hydraulic checks 110 and 111 are opened and the rate of return movement of the pistons 97 is governed only by the metering valve 138 which preferably is set to govern the speed of such return movement only to the extent that smooth operation is not affected by the speed. As the pistons 97 approach the limit of their return travel, the finger 170 engages the linkage 171 to close the switch 168 momentarily to energize the solenoid 145 for a length of time sufiicient to move the valve spool or element 144 to direct flow of air under pressure through the conduit 141 to the valve 125 to cause the piston 128 thereof to raise the valve element 127 to its position shown in FIG. 10. Closing of the switch 168 occurs slightly before closing of the switch 165 so that air under pressure is admitted to the bottoms of the cylinders 41) and 58 to cause raising of the pistons 42 and 6t) and consequent opening of the switch 164 before the solenoid 154 can again become energized. Vtith the raising of the pistons 42 and 69 and parts associated therewith, the cycle of operation is completed and the formed sheet may be removed from the machine and subsequently adhered to the backing structure G and projecting edges thereof trimmed away.

It will be appreciated that, should it be desired to dispense with the curved portion D at the upper edge of the splash back portion C, it is only necessary that the workpiece engaging member 9% be removed from the machine. Further, with the arrangement of the several forming dies 47, 71 and 72, and the tangential engagement of the several curved surfaces thereof with the adjacent surface portions of the plastic sheet A, I have been enabled to post-form C stage thermo setting plastic sheets relatively rapidly and with no loss due to breakage of the workpiece at the bends thereof. Moreover, by projecting the forming dies into the clamped sheet, and simultaneously applying heat to the surface of the work sheet at both sides of the line of tangential engagement, I am able to form the sheet of plastic material over smaller radii than has been heretofore done without causing fracture of the sheet material.

My invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and while I have shown and described a commercial embodiment of my post-forming machine, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention, as defined in the claims.

What I claim is:

1. In a machine for post-forming resinous plastic sheet material,

(a) a frame structure,

(b) an elongated table on said frame structure for supporting a sheet of post-formable plastic material extending longitudinally of said table and having side edge portions projecting laterally outwardly of opposite longitudinal side edges of said table,

(0) laterally spaced clamping elements extending lon gitudinally of said table in overlying relation thereto adjacent said longitudinal side edges of said table and mounted for movements toward and away from said table,

(0?) one of said clamping elements comprising a forming die,

(2) second and third forming dies, one each disposed adjacent an opposite longitudinal side edge of said table and extending longitudinally thereof,

(1) means mounting said second and third forming dies for movements between retracted lower positions and generally upwardly projected positions, each of said second and third forming dies engaging an undersurface portion of said sheet when said sheet is placed on said table and held by said clamping means,

(g) power operated means for imparting movement to said second and third forming dies between said retracted and projected positions thereof,

(h) means for heating at least some of said forming dies,

(i) and a sheet engaging element operatively connected to one of said clamping elements and cooperating with an adjacent one of said second and third forming dies to bend the adjacent side edge portion of said sheet when said second and third forming dies are moved toward said projected positions thereof, one of said second and third forming dies cooperating with said first mentioned forming die to bend said sheet intermediate said side edge portions of the sheet.

2. The structure defined in claim 1 in which each of said forming dies defines a cross sectionally arcuate surface initially tangentially engaging an adjacent surface portion of said sheet, whereby heat radiating from the heated ones of said forming dies is directed toward said sheet at opposite sides of the line of tangential engagement between each of said heated forming dies and said sheet, to facilitate bending of the sheet at said opposite sides of said line of tangential contact.

3. The structure defined in claim 1 in further combination with control means for said power operated means responsive to clamping movements of said clamping elements to cause said power operated means to impart simultaneous movements to said second and third forming dies in projected sheet bending directions, movements of said second and third forming dies in retracting directions away from said sheet, and sheet releasing movements to said clamping elements, in succession.

4. The structure defined in claim 1 in which said means mounting the second and third forming dies comprises a pair of mounting members each carrying a different one of said second and third forming dies and each pivotally connected to an opposite side of said table on a horizontal axis extending longitudinally of the table.

5. The structure defined in claim 1 in which said tablecomprises a pair of elongated table sections one mounted on said frame structure for movements laterally toward and away from the other thereof, one of said clamping elements and one of said second and third forming dies being mounted for common lateral move ments with said one of the table sections, and in further combination with means for imparting said common movements to said one of the table sections and its cooperating clamping element. v

6. The structure defined in claiml in which said power-operated means comprises,

(a) a pair of fluid pressure cylinders, one for each of said second and third forming dies and extending longitudinally of each thereof,

(b) a pair of elongated piston rod structures, one each extending axially from a different one of said cylinders,

(c) and a plurality of axially spaced cam elements and a like plurality of cooperating cam follower elements, some thereof being operatively connected to said piston rod structures and some thereof being operatively connected to said mounting means for the second and third forming dies, said cam elements and cam follower elements being responsive to said axial movements of saidlpiston rod structures to (c) and means providing fluid circuits between opposed ends of said control cylinders and including metering Valves and check-valve means arranged to control the rate of fluid flow in opposite directions between opposite ends of said control cylinders, whereby to retard the speed of projection movement of said second and third forming dies and to permit relatively free retracting movement of said second and third forming dies. 7 v

8. The structure defined in claim 1 in which one of said second and third forming dies is disposed slightly above the level of said table in its lower retracted position, whereby to engage the undersurface of said sheet on said table prior to projecting movement of said one of the forming dies, the other of said second and third forming dies in its retracted position being disposed at a level 'below that of said table, said sheet-engaging element projecting below the level of said table when said clamping elements are disposed in clamping engagement with said sheet to bend the adjacent edge portion of said sheet into engagement with said other of said second and thirdforming dies in its retracted position, whereby all of said forming dies engage said sheet prior to movement of said second and third forming dies toward the projected positions thereof.

9. The structure defined in claim 1 in which said power-operated means comprises a pair of fluid pressure operated cylinders and connections therebetween and respective ones of said second and third forming dies, and in further combination with fluid pressure operated means for moving said clamping means into and out of clamping engagement with said sheet on said table, and control means for said fluid pressure operated means and said cylinders and including,

(a) valve means, (b) electrically operated actuators for said valve means, 7

(c) and a time-delay device operative responsive to movement of clamping elements to their clamping positions to eifect a predetermined time interval between said clamping movement of the clamping elements andmovement of said second and third forming dies toward their projected sheet forming positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,739,636 Tyler Mar. 27, 1956 2,739,637 Tyler Mar. 27, 1956 2,937,689 Peterson May 24, 1960 3,009,201 Hansen Nov. 4, 1961 

1. IN A MACHINE FOR POST-FORMING RESINOUS PLASTIC SHEET MATERIAL, (A) A FRAME STRUCTURE, (B) AN ELONGATED TABLE ON SAID FRAME STRUCTURE FOR SUPPORTING A SHEET OF POST-FORMABLE PLASTIC MATERIAL EXTENDING LONGITUDINALLY OF SAID TABLE AND HAVING SIDE EDGE PORTIONS PROJECTING LATERALLY OUTWARDLY OF OPPOSITE LONGITUDINAL SIDE EDGES OF SAID TABLE, (C) LATERALLY SPACED CLAMPING ELEMENTS EXTENDING LONGITUDINALLY OF SAID TABLE IN OVERLYING RELATION THERETO ADJACENT SAID LONGITUDINAL SIDE EDGES OF SAID TABLE AND MOUNTED FOR MOVEMENTS TOWARD AND AWAY FROM SAID TABLE, (D) ONE OF SAID CLAMPING ELEMENTS COMPRISING A FORMING DIE, (E) SECOND AND THIRD FORMING DIES, ONE EACH DISPOSED ADJACENT AN OPPOSITE LONGITUDINAL SIDE EDGE OF SAID TABLE AND EXTENDING LONGITUDINALLY THEREOF, (F) MEANS MOUNTING SAID SECOND AND THIRD FORMING DIES FOR MOVEMENTS BETWEEN RETRACTED LOWER POSITIONS AND GENERALLY UPWARDLY PROJECTED POSITIONS, EACH OF SAID SECOND AND THIRD FORMING DIES ENGAGING AN UNDERSURFACE PORTION OF SAID SHEET WHEN SAID SHEET IS PLACED ON SAID TABLE AND HELD BY SAID CLAMPING MEANS, (G) POWER OPERATED MEANS FOR IMPARTING MOVEMENT TO SAID SECOND AND THIRD FORMING DIES BETWEEN SAID RETRACTED AND PROJECTED POSITIONS THEREOF, (H) MEANS FOR HEATING AT LEAST SOME OF SAID FORMING DIES, (I) AND A SHEET ENGAGING ELEMENT OPERATIVELY CONNECTED TO ONE OF SAID CLAMPING ELEMENTS AND COOPERATING WITH AN ADJACENT ONE OF SAID SECOND AND THIRD FORMING DIES TO BEND THE ADJACENT SIDE EDGE PORTION OF SAID SHEET WHEN SAID SECOND AND THIRD FORMING DIES ARE MOVED TOWARD SAID PROJECTED POSITIONS THEREOF, ONE OF SAID SECOND AND THIRD FORMING DIES COOPERATING WITH SAID FIRST MENTIONED FORMING DIE TO BEND SAID SHEET INTERMEDIATE SAID SIDE EDGE PORTIONS OF THE SHEET. 